(1) Field of the Invention
This invention relates to underwater bodies and scoops fixed therein for ingesting water as the body moves through a water environment, and is directed more particularly to such a scoop which limits hydrodynamic cavitation and, thereby, the consequences thereof.
(2) Description of the Prior Art
Three types of water inlets are used in underwater bodies such as torpedoes, unmanned underwater vehicles, submarines, and the underwater hull portions of surface vessels: (1) ports flush with the surface of the body, (2) protruding scoops, and (3) recessed scoops, that is, scoops extending underneath the outer surface of the body.
Flush ports are not effective for many applications, due primarily to the lack of notable dynamic pressure head. Protruding scoops, while generally effective with respect to inlet flow volume and pressure head, are undesirable in many applications because of drag created by the protrusion beyond the exterior of the body and because of excess cavitation generated thereby. Recessed scoops represent a compromise between flush ports and protruding scoops. Recessed scoops provide better pressure head and intake volume than do flush ports, and better cavitation performance than protruding scoops, but, conversely, suffer less pressure head and intake volume than protruding scoops and more cavitation than is present in flush ports. Consequently, there is a need for a recessed scoop wherein pressure head and intake volume are maximized and cavitation is minimized.
One of the situations in which cavitation presents a significant problem is the operation of an underwater vehicle at the shallower depths of the littoral regions of the ocean. Underwater vehicles operate in these regions for among other reasons, anti-mine naval missions.
Cavitation causes the undesired effects of hydrodynamic drag, noise vibration, and enhancement of corrosion and pitting due to impulse effects of cavitation behavior at the boundary between the water and the hull of a body in motion.